1. Field of the Invention
The present invention relates to an electronic level to automatically obtain a height and to a leveling rod (or a staff) which is used together with the electronic level.
2. Description of the Related Art
As this kind of electronic level and a leveling rod, there is known, for example, in Japanese Published Examined Patent Application No. 18042/1993 or Japanese Published Unexamined Patent Application No. 4959/1995, a leveling rod for use with an electronic level having a plurality of bar marks (i.e., marks in the shape of bars) which are provided in a longitudinal direction of the leveling rod. In this leveling rod, bar marks whose pitches between respectively adjoining bar marks are appropriately varied with one another are collimated by the electronic level. Then a wave form which is obtained from an array pattern of the bar marks in the collimated position is compared inside the electronic level with a wave form that is stored in advance in the electronic level. From a position in which the wave forms coincide with each other, the height of the collimated position is obtained.
The wave form to be obtained from the array pattern of the bar marks that are attached to the leveling rod varies in its size with the distance between the leveling rod and the electronic level, or with the magnification of the electronic level. In the above-described conventional electronic level and the leveling rod, the collimated position is obtained by coinciding the wave form to be obtained from the array pattern of the bar marks with the wave form that is stored in advance in the electronic level. It follows that, before comparing the wave forms with each other, they must be corrected to a predetermined size. However, in order to perform this kind of correction, the distance between the leveling rod and the electronic level must be obtained, resulting in a disadvantage in that a long time is required to make computation for the correction.
The present invention has an object of eliminating the above-described disadvantage.